Tamoxifen after Mastectomy to prevent development of CA in other breast?

What is the current thinking on Tamoxifen use for high nuclear grade,multifocal,comedonecrosis DCIS ( 4.0cm with tiny margins <mm) treated with MRM with nodes negative?  Is there any benefit to its use to irradicate possible microinvasion or to prevent cancer from developing in the other breast?  Thanks, Eamona

[CCF-RN,MSN-rf]

Dear eamona:  Much of the research done on tamoxifen in DCIS has been done on women who have had lumpectomys + radiation.  The addition of tamoxifen reduced the incidence of non-invasive and invasive recurrences, second cancers in the opposite breast, and metastasis.  Given the reduction of second cancers in the opposite breast and metastasis, it would seem valid to consider the addition of tamoxifen after mastectomy for DCIS.